Filled polymeric materials have been known to provide decorative and protective surfaces to walls. For instance, it has been known to coat masonry units filled with polyesters and to form walls therefrom. The basic patent on the use of polyester as coatings for masonry units is U.S. Pat. No. 2,751,775 to Sergovic and assigned to the assignee of the present application. Over the years, a number of improvements in the coating compositions for the masonry building units have been developed. For instance, U.S. Pat. No. 3,328,231 to Sergovic and assigned to the assignee of the present application, discloses a glazed masonry building block made of a cured composition of an unsaturated polyester resin and sand in which the sand comprises at least 50% by weight of the coating composition. The unsaturated polyester is derived from a reaction between a dicarboxylic acid, such as phthalic, maleic, fumaric, adipic, pimelic, suberic, itaconic, citraconic, succinic acids, and/or an anhydride thereof, and a polyhydric alcohol such as ethylene glycol, diethylene glycol, and propylene glycol. Also present in such compositions is an unsaturated monomer, such as methyl methacrylate, styrene, diallyl phthalate, t-butyl styrene, and alphamethyl styrene. Furthermore, U.S. Pat. No. 4,031,289 to Sergovic discloses coated masonry building blocks, articles and compositions therefore that employ various pigments and chemicals in combination with various resinous compositions to provide stain resistance when subjected to high moisture conditions and/or staining media. The disclosures of the above mentioned U.S. Pat. Nos. 2,751,775, 3,328,231 and 4,031,289 are incorporated herein by reference.
Constructing walls with glazed masonry building units presents particular problems with respect to the formation of the outside corners of the wall structures. For example, glazed cinder or concrete blocks at corners and intersecting wall planes must be glazed on more than one side, in particular one face and one end or one face and one top provided that they are intersecting, in order for the glaze material to show when turning a corner. However, attempts to glaze two intersecting sides of a masonry block have not been entirely successful and have suffered from a number of problems. For example, the percent of factory culls or rejects generated when making a corner or cap block with two or more surfaces glazed simultaneously is significantly greater than the percent of culls generated when glazing a single face or plane to form a straight wall unit (referred to in the art as "stretchers").
The vertical space between the end of the mold and the concrete block requires special care to assure the removal of entrapped air while filling the space with the glazing material. This results in air bubbles which become pinholes in the return end of corner units. Also, the differences in sand settlement can cause unsightly lines at the intersecting planes of the corner.
Rejected glazed corner blocks result in a 5% to about 10% loss as compared to only a 0.5% to about 2% loss for coated "stretchers." In particular, defects in the finished products are manifested as the formation of unsightly lines at the intersecting planes of the decorative surfaces of the corner units, unsightly pin holes and differences in the color appearance between the intersecting surface planes of such blocks.
One attempt to overcome the problems associated with constructing the outside corners is disclosed in U.S. Pat. No. 4,329,822 to Russell and assigned to the assignee of the present application. In particular, U.S. Pat. No. 4,329,822 discloses a corner wall facing unit that includes a unit that it is not supported by a concrete block and must be supported using a non-block supported wall system or wire mesh and are time-consuming to erect. Although such a system has been quite effective, such non-self-supporting units tended to be relatively heavy for their size which requires the use of temporary wedges to prevent slippage and sagging in the mortar used between the wall units during erection. Also, such units require special installation care, and do not assure structural integrity equal to this system and other conventional systems.
Moreover, turning a corner, e.g. a 90.degree. corner or more, has been carried out by employing a single piece angled glazed block in conjunction with a glazed straight wall unit (see FIG. 7). Such a corner would be used to create a wall angle in the exposed face by employing only one angled glazed block and will always be connected to a straight wall unit without the use of a second corner piece or angled glazed block. The return employed on these prior angled glazed blocks are relatively deep, i.e. at least about 33/4". The use of such a single piece angled glazed block normally requires a fill piece adding to the complexity of the arrangement. The prior angled glazed blocks are merely an angled version of the 90.degree. 4", 6", 8" or 12" single corner square or rounded units.